Remote-controlled vehicles can be used for carrying tools, or other items, and can travel into hazardous or confined areas where human workers cannot go. However, designing vehicles capable of travelling through, and operating in, enclosed spaces such as within pipes, channels, ducts or other conduits, has presented difficulties.
One class of such vehicles are those which are self-propelled by a linear actuator, or the like. These vehicles include two bodies connected by the actuator for moving the bodies towards and away from each other, by which movement the vehicle is able to propel itself through the pipe in a stepwise manner. The bodies may include bristles or bladders for engagement with the wall of the pipe. A disadvantage with such vehicles is that they are unsuited to provide strong frictional engagement with the pipe, such as may be required when performing different operations within the pipe, such as clearing an obstruction.
U.S. Pat. No. 6,415,722 addresses this drawback and describes a vehicle propelled by a linear hydraulic actuator having a central cylinder with a through-extending piston rod. Three sets of rigid legs are fixed to the actuator and may be extended by actuators which control engagement with the walls of the pipe. Two sets of legs are fixed to opposing ends of the rod and the third set is fixed to the cylinder. The vehicle is powered and controlled remotely and may be stepped along the conduit by alternately fixing the cylinder and rod by means of the attached legs while moving the piston rod. A mechanical breakdown of the vehicle within a pipe can result in considerable cost and inconvenience and thus mechanical complexity, with the attendant risk of a malfunction, is disadvantageous where it does not provide significantly improved performance. This prior art vehicle is designed for use in oil pipelines and is of relatively complex construction making it potentially expensive and difficult to operate and maintain. In particular, the complexity of this vehicle is increased by the provision of separate hydraulic actuators for extending each of the nine legs. Independent actuation of each leg in the vehicle is also disadvantageous where it is desired to accurately centre the vehicle within the pipe.
It will be understood that there is a need for a vehicle which may be manufactured at relatively low cost, making it a viable option for uses such as cleaning of drains. Another important consideration in the design of vehicles of this type is the ability to accommodate tools and associated apparatus for performing operations inside the pipe. The vehicle should be compact to provide room for such apparatus, making efficient use of the space available.
All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.
It is acknowledged that the term ‘comprise’ may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term ‘comprise’ shall have an inclusive meaning—i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term ‘comprised’ or ‘comprising’ is used in relation to one or more steps in a method or process.
It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.